Difference Between Bacterial and Fungal Colonies

The main difference between bacterial and fungal colonies is that bacterial colonies are small, smooth or rough colonies with defined margins while fungal colonies are large colonies with a fuzzy appearance. Furthermore, bacterial colonies look wet and shiny while fungal colonies are powder-like. 

Bacterial and fungal colonies refer to the appearance of growth of bacteria and fungi on a solid, nutrient agar. Colony morphology is the area that studies the characteristics of colonies. Characteristics of colonies include colony form, elevation, margin, surface, capacity, and chromogenesis.  

Key Areas Covered 

1. What are Bacterial Colonies
     – Definition, Facts,  Appearance 
2. What are Fungal Colonies
     – Definition, Facts, Appearance 
3. What are the Similarities Between Bacterial and Fungal Colonies
     – Outline of Common Features
4. What is the Difference Between Bacterial and Fungal Colonies
     – Comparison of Key Differences

Key Terms: Bacterial Colonies, Form, Fungal Colonies, Size, Texture 

What are Bacterial Colonies 

Bacterial colonies are a mass of bacterial cells divided from a single bacterium on the solid medium. All bacteria within the colony are genetically alike and can be called a clone. Most bacterial colonies are circular or irregular in shape. Some of them are actinomycetes filamentous or rhizoid. Most bacterial colonies are tiny and less than 1 mm in diameter. Hence, they are called punctiform (pin-point). They have a defined margin as well. The microscope can be used in order to observe the edge. The colour of the colony varies with the species. They can be white, buff, red, purple, etc.

Figure 1: Yersinia enterocolitica Colonies 

The surface of the bacterial colonies can be smooth, glistening, rough, dull, or rugose (wrinkled). The texture of them can be butyrous (buttery), viscid (sticks to loop, hard to get off), brittle/friable (dry, breaks apart) or mucoid (sticky, mucus-like).  

What are Fungal Colonies 

Fungal colonies are either a mass of cells of unicellular fungi or fungal hyphae of multicellular fungi. Fungal colonies made up of unicellular fungi resemble bacterial colonies on solid media. However, fungal colonies made up of multicellular fungi are fuzzy. The form of these colonies can be either filamentous or rhizoid. They often appear in whitish gray colour. They turn into different colours from the centre with the growth of the colony.

Figure 2: Yarrowia lipolytica Colonies  

Similarities Between Bacterial and Fungal Colonies 

• Bacterial and fungal colonies are the growth forms on solid nutrient agar. 
• They exhibit specific characteristics to the organism that forms the colony. 
• The colour of the colony depends on the type of microorganism that forms the colony. 
• Both can be used in the identification of the microorganisms. 

Difference Between Bacterial and Fungal Colonies 

Definition 

Bacterial colonies refer to a visible mass of cells arisen from a single bacterial cell while fungal colonies refer to a mass of thread-like hyphae.  

Unicellular or Multicellular 

Bacterial colonies are made up of unicellular organisms while fungal colonies can be made up of either unicellular or multicellular organisms.  

Made up of  

Bacterial colonies are made up of a mass of bacterial cells resulted from the division of a single bacterium while fungal colonies are made up of fungal hyphae produced by a single spore.  

Size of the colony  

Bacterial colonies are small while most of the fungal colonies that develop hyphae are large. 

Appearance 

Bacterial colonies have a smooth or rough appearance while fungal colonies have a fuzzy appearance. This is one main difference between bacterial and fungal colonies.

Margin 

Bacterial colonies have a defined margin while fungal colonies have a filamentous margin. 

Texture 

Bacterial colonies look wet and shiny while fungal colonies are powder-like. 

Form 

Bacterial colonies are circular or irregular while fungal colonies are filamentous or rhizoid. 

pH 

Bacterial colonies grow within the pH 5-9 (optimum 7) while fungal colonies grow within the pH 5-6. 

Conclusion 

Bacterial colonies are small, mostly rounded, shiny colonies made up of a bacterial clone. On the other hand, fungal colonies are large, fuzzy colonies mostly formed from the fungal hyphae. The main difference between bacterial and fungal colonies is the form and the texture of colonies. 

Reference:

1. “8: Bacterial Colony Morphology.” Biology LibreTexts, Libretexts, 3 Jan. 2018, Available Here     
2. Moore, David, et al. “4.6 Morphological Differentiation of Fungal Colonies.” 21st Century Guidebook to Fungi, 1 Dec. 2008, Available Here

Image Courtesy:

1. “Yersinia enterocolitica colonies Hektoen” By CDC – This media comes from the Centers for Disease Control and Prevention’s Public Health Image Library (PHIL), with identification number #6707. (Public Domain) via Commons Wikimedia    
2. “Yarrowia lipolytica YGC colonies 56” By A doubt – Own work (CC BY-SA 4.0) via Commons Wikimedia